A software-defined MF-TDMA multi-beam access method and device

Abstract

This invention discloses a software-defined MF-TDMA multi-beam access method and apparatus, belonging to the field of satellite communication technology. The network control center generates software-defined control commands based on user resource requests and the overall network service load. The gateway station encapsulates the forward data according to the control commands and sends the encapsulated data to a low-Earth orbit (LEO) satellite using time-division multiplexing technology. The LEO satellite performs beam-level switching on the encapsulated data according to a beam-hopping pattern and sends the switched data to the user terminal via the corresponding downlink beam. The user terminal allocates resources based on the received data according to the control commands and sends the multi-beam uplink signal to the LEO satellite. This invention overcomes the shortcomings of existing static or semi-static resource allocation methods in terms of insufficient dynamic adaptability. It can flexibly schedule resources according to user requests and the overall network service status, significantly improving resource utilization, enabling flexible beam switching, and effectively improving transmission efficiency.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication technology, specifically relating to a software-defined MF-TDMA multi-beam access method and apparatus. Background Technology

[0002] With the rapid development of high-throughput satellites and low-Earth orbit constellations, satellite communication is evolving towards high capacity, wide coverage, and flexible access. Multi-beam antenna technology, through spatial multiplexing, divides space into multiple isolated point beams, significantly improving system spectral efficiency. Multi-frequency time-division multiple access (MF-TDMA), as the mainstream access system, divides communication resources into fine-grained segments in frequency and time dimensions, supporting efficient channel sharing among multiple users. Specifically, time-division multiple access divides the same frequency band into multiple time slots for different users to use in a time-division manner, while frequency-division multiple access divides the total spectrum into non-overlapping sub-frequency bands and allocates them to different users. Multi-beam antennas can simultaneously generate multiple independent and controllable beams, forming beams pointing to different regions in space by controlling the phase and amplitude of each radiating element, thereby improving communication capacity and anti-interference capabilities.

[0003] Software-defined networking (SDN) separates the control plane from the data forwarding plane, enabling centralized software control and providing a new approach for flexible scheduling of satellite communication resources. However, most existing satellite communication systems employ static or semi-static resource allocation methods, with control primarily concentrated in the forward link, resulting in insufficient dynamic adaptation capabilities for network-wide link resource allocation. In terms of satellite payload architecture, traditional curved-tube transparent forwarding satellites can only perform frequency conversion amplification and lack onboard regeneration processing capabilities, making it impossible to flexibly exchange and reconstruct data between multiple beams according to real-time service requirements, thus limiting the fine-grained management of beam resources. Regarding duplexing, existing beam-hopping scenarios generally employ frequency division duplex (FDD), requiring both the satellite and the terminal to operate in symmetrical frequency bands. This not only increases the number of onboard and ground terminal antennas but also hinders the development of asymmetric uplink and downlink services. Furthermore, if time division duplex (TDD) is adopted to reduce equipment complexity and support asymmetric transmission, it lacks reasonable guard intervals and dynamic delay compensation mechanisms, easily leading to severe uplink and downlink co-channel interference and multi-user time slot collisions.

[0004] Therefore, how to provide an effective technical solution to address the technical problems of insufficient dynamic adaptation capability, unfavorable conditions for carrying out uplink and downlink asymmetric services, and beam differential time delay interference control under TDD mode has become an urgent technical challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a software-defined MF-TDMA multi-beam access method and apparatus to solve the above-mentioned problems existing in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a software-defined MF-TDMA multi-beam access method, applied to a communication system including a network control center, gateway station, low-Earth orbit satellite, and user terminal, comprising: The network control center obtains the user's resource request and generates software-defined control commands based on the user's resource request and the overall network service load. The control commands include beam switching patterns. The control commands are sent to the low-Earth orbit satellite through the gateway station and simultaneously to the user terminal. The gateway station acquires forward data and encapsulates the forward data according to control commands to obtain encapsulated data. Using time-division multiplexing technology, the encapsulated data is sent to the low-Earth orbit satellite. Low-Earth orbit satellites perform beam-level switching on the encapsulated data according to the beam hopping pattern, and then transmit the switched data to the user terminal via the downlink beam. The user terminal allocates resources to the received exchanged data based on control commands, obtains multi-beam uplink signals, and transmits the multi-beam uplink signals to low-Earth orbit satellites through multi-frequency time division multiple access technology; The low-orbit satellite performs on-board regeneration processing on the multi-beam uplink signal and transmits it back to the gateway station via the satellite-to-ground link.

[0007] In one possible design, the multi-beam uplink signal includes frequency division multiple access (FDMA) signal, time division multiple access (TDMA) signal, and code division multiple access (CDMA) signal; the low-Earth orbit satellite performs on-board regeneration processing on the multi-beam uplink signal and transmits it back to the gateway station via a satellite-to-ground link, including: A low-pass filter is used to separate the multi-beam uplink signal into multiple frequency division multiple access signals; For each frequency division multiple access signal, a matched filter is used to extract the time slot synchronization of the time division multiple access signal to obtain a burst pulse signal. Based on the burst pulse signal, a despreader and a delay-locked loop are used to track the code phase of the code division multiple access signal to separate the burst signals of each user. For each user's burst signal, the initial carrier phase is estimated by maximum likelihood estimation to complete carrier synchronization and obtain the estimated carrier phase. Based on the estimated carrier phase, the burst signals of each user are quadrature demodulated to obtain the baseband symbol sequence. The differential phase of adjacent symbols in the baseband symbol sequence is estimated and corrected for frequency offset to obtain a frequency offset-free symbol sequence. The symbol sequence without frequency offset is demodulated and decoded to obtain user data packets. The user data packets are reconstructed based on control commands to obtain downlink data streams, which are then sent to the gateway station.

[0008] In one possible design, after demodulating and decoding the frequency-offset-free symbol sequence, the following is also included: Obtain data packets and target address information for each user; Low-Earth orbit satellites aggregate user data packets belonging to the same downlink beam according to a pre-set exchange table, and then re-encode and modulate the channel to obtain a reconstructed downlink data stream.

[0009] In one possible design, the network control center obtains the user's resource requests, including: The network control center obtains the number of time slot requests required for each user's reverse transmission, divides each user's time slot requests into multiple time slot blocks according to consecutive time slots, and sorts the multiple time slot blocks in descending order according to the size of the time slot blocks to obtain a set of time slot blocks to be allocated. Initialize all available carriers in the communication system in numerical order and record the remaining time slots for each carrier; According to the preset allocation rules, the largest time slot block in the set of time slot blocks to be allocated is allocated to the carrier with the most remaining time slots. If multiple carriers have the same number of remaining time slots, the time slot block to be allocated is allocated to the carrier with the smallest number. After one round of allocation is completed, if there are still unallocated time slot blocks, the carriers are selected in descending order of the remaining time slots of each carrier for the next round of allocation, until all time slot blocks are allocated or the remaining time slots of all carriers are zero, and the user's resource request is obtained.

[0010] In one possible design, the network control center obtains the number of time slot requests required for each user's reverse transmission, including: The network control center obtains the transmission rate requirements of each user uploaded by the user terminal. The number of time slots required for the user's reverse transmission is calculated based on the user's transmission rate requirements, the preset frame length, and the effective data volume carried per time slot. The expression for the number of time slots required for the user's reverse transmission is as follows: ; In the formula, The number of time slot requests required for the reverse transmission of the i-th user. For the ceiling function, For the transmission rate requirement of the i-th user, For the preset frame length, The effective amount of data carried per time slot.

[0011] In one possible design, the beam hopping pattern is a time slot block of each wave position within a hopping beam cycle, wherein each wave position's time slot block consists of an uplink time slot, a downlink time slot, and a guard interval. The duration of the protection interval is the difference between the maximum and minimum satellite-to-ground transmission delay within the corresponding wavelength.

[0012] In one possible design, software-defined control commands are generated based on user resource requests and overall network service load, including: Within a hopping beam cycle, the uplink / downlink switching mechanism is used to determine the number of consecutive time slots allocated after each switching. With the goal of maximizing the number of available time slots, a time slot calculation model is constructed, and the expression of the time slot calculation model is as follows: ; In the formula, Number of available time slots This represents the total number of time slots within a hopping beam period. For the number of switching times, For protection intervals; The time slot calculation model is solved to select a time slot number from the minimum or maximum demand of the current wave positions to be allocated as a benchmark for allocation, and the utilization rate after allocation is calculated. The time slot number that maximizes the utilization rate is selected as the final time slot number for this allocation, and software-defined control instructions are generated based on the final time slot number for this allocation.

[0013] In one possible design, the control commands are sent to a dedicated management channel of the low-Earth orbit satellite via a gateway station, and the network control center updates the control commands in real time according to changes in services.

[0014] Secondly, the present invention provides a software-defined MF-TDMA multi-beam access device, comprising: The network control center is used to acquire users' resource requests and generate software-defined control commands based on the users' resource requests and the overall network service load. The control commands include beam switching patterns. The control commands are sent to low-Earth orbit satellites through gateway stations and simultaneously to user terminals. The gateway station is used to acquire forward data and encapsulate the forward data according to control commands to obtain encapsulated data. Using time division multiplexing technology, the encapsulated data is sent to the low-Earth orbit satellite. Low-Earth orbit satellites are used to perform beam-level switching on encapsulated data according to beam hopping patterns and then transmit the switched data to user terminals via the corresponding downlink beams. The user terminal is used to allocate resources to the received exchanged data based on control commands, obtain multi-beam uplink signals, and transmit the multi-beam uplink signals to low-orbit satellites through multi-frequency time division multiple access technology. Low-orbit satellites are also used for on-board regeneration of multi-beam uplink signals and back to the gateway station via a satellite-to-ground link.

[0015] Thirdly, the present invention provides a software-defined MF-TDMA multi-beam access device, comprising a memory, a processor, and a transceiver connected in sequence, wherein the memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the software-defined MF-TDMA multi-beam access method as described in the first aspect above.

[0016] Fourthly, the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, perform the software-defined MF-TDMA multi-beam access method as described in the first aspect above.

[0017] Fifthly, the present invention provides a computer program product containing instructions that, when executed on a computer, cause the computer to perform the software-defined MF-TDMA multi-beam access method as described in the first aspect above.

[0018] The beneficial effects of this invention are as follows: This invention discloses a software-defined MF-TDMA multi-beam access method and apparatus. The network control center obtains the user's resource request and generates a software-defined control command based on the user's resource request and the overall network service load. The control command includes a beam hopping pattern. The control command is sent to a low-Earth orbit satellite through a gateway station and simultaneously to a user terminal. The gateway station obtains forward data and encapsulates the forward data according to the control command to obtain encapsulated data. Using time-division multiplexing technology, the encapsulated data is sent to the low-Earth orbit satellite. The low-Earth orbit satellite performs beam-level switching on the encapsulated data according to the beam hopping pattern and sends the switched data to the user terminal through the corresponding downlink beam. The user terminal allocates resources to the received switched data based on the control command to obtain a multi-beam uplink signal and sends the multi-beam uplink signal to the low-Earth orbit satellite through multi-frequency time-division multiple access technology. This invention generates software-defined control commands through a network control center, centrally manages and distributes these commands in real time, overcoming the shortcomings of existing static or semi-static resource allocation methods in terms of insufficient dynamic adaptability. This enables satellite communication systems to flexibly schedule resources based on user requests and the overall network service status, significantly improving resource utilization. On-board regeneration processing breaks through the transparent forwarding bottleneck, enabling flexible beam switching. Low-Earth orbit satellites separate uplink multi-beam signals and reconstruct downlink data streams according to control commands, giving the satellites on-board regeneration switching capabilities. This allows for flexible data exchange between multiple beams based on real-time service needs, fine-grained management of beam resources, and effective improvement in transmission efficiency. Simultaneously, it effectively suppresses TDD co-channel interference and multi-user time slot collisions. Uplink and downlink protection intervals are set based on the maximum differential satellite-to-ground transmission delay within the beam coverage area, combined with user terminal time advance compensation, to achieve uplink signal time slot alignment at the satellite, ensuring the reliability and transmission quality of multi-beam access. Attached Figure Description

[0019] Figure 1 A flowchart illustrating a software-defined MF-TDMA multi-beam access method provided in one embodiment of the present invention; Figure 2 A block diagram of a software-defined MF-TDMA multi-beam access device provided in one embodiment of the present invention; Figure 3 The diagram shows the structure of a software-defined MF-TDMA multi-beam access device according to another embodiment of the present invention. Detailed Implementation

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0021] It should be understood that although the terms first, second, etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit, without departing from the scope of the exemplary embodiments of the invention.

[0022] It should be understood that the term "and / or" that may appear in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" that may appear in this document describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this document generally indicates that the related objects before and after it are in an "or" relationship.

[0023] Example: like Figure 1 As shown, the first aspect of this embodiment provides a software-defined MF-TDMA multi-beam access method, applied to a communication system including a network control center, gateway station, low-Earth orbit satellite, and user terminal. It can be executed, but is not limited to, by a computer device or virtual machine with certain computing resources, such as a personal computer or smartphone, or by a virtual machine. The MF-TDMA multi-beam access method includes, but is not limited to, the following steps: S1. The network control center obtains the user's resource request and generates software-defined control instructions based on the user's resource request and the overall network service load. The control instructions include a beam-hopping pattern. The control instructions are sent to the low-Earth orbit satellite through the gateway station and simultaneously sent to the user terminal. It should be noted that the beam hopping pattern is a time slot block for each wave position within a beam hopping cycle. Each wave position's time slot block consists of an uplink time slot, a downlink time slot, and a guard interval. The duration of the guard interval is the difference between the maximum and minimum satellite-to-ground transmission delay within the corresponding wave position. The control commands include, but are not limited to, the beam hopping pattern, the uplink / downlink time slot allocation table, and the frequency configuration scheme. The beam hopping pattern defines the lighting sequence of each wave position within the beam hopping cycle. The uplink / downlink time slot allocation table specifies the number and arrangement of uplink and downlink time slots during each lighting period. The frequency configuration scheme specifies the carrier frequency band and reuse relationship used by each beam.

[0024] In practice, the communication system includes a network control center, gateway stations, low-Earth orbit (LEO) satellites, and user terminals. The network control center is deployed on the ground and is responsible for the overall network resource management. It generates software-defined control commands and sends them to the gateway stations via ground links. The gateway stations are interconnected with the LEO satellites via feeder links and are responsible for forwarding control commands and transmitting and receiving service data. The LEO satellites operate in low Earth orbit and are equipped with multi-beam antennas, onboard regeneration processing payloads, and beam-hopping controllers, enabling rapid switching between different frequency bands. User terminals are distributed across the coverage areas of each frequency band and support multi-frequency time-division multiple access.

[0025] Specifically, in step S1, the network control center obtains the user's resource request, including: S11. The network control center obtains the number of time slot requests required for each user's reverse transmission, divides each user's time slot request into multiple time slot blocks according to continuous time slots, and sorts the multiple time slot blocks in descending order according to the size of the time slot blocks to obtain a set of time slot blocks to be allocated. S12. Initialize all available carriers in the communication system in numerical order and record the remaining time slots for each carrier; S13. According to the preset allocation rules, the largest time slot block in the set of time slot blocks to be allocated is allocated to the carrier with the most remaining time slots. If multiple carriers have the same number of remaining time slots, the time slot block to be allocated is allocated to the carrier with the smallest number. S14. After completing one round of allocation, if there are still unallocated time slot blocks, the carriers are selected in descending order of the remaining time slots of each carrier for the next round of allocation, until all time slot blocks are allocated or the remaining time slots of all carriers are zero, and the user's resource request is obtained.

[0026] In practice, the preset allocation rules include at least the following: the time slots allocated to each user must be within the same carrier and maintain temporal continuity; the total number of time slots allocated on each carrier must not exceed the maximum time slot capacity of that carrier; and the total power allocated on each carrier must not exceed the upper limit of that carrier's power.

[0027] Furthermore, in step S1, based on the user's resource requests and the overall network service load, software-defined control instructions are generated, including: S15. Within a hopping beam cycle, the uplink / downlink switching mechanism is used to determine the number of consecutive time slots allocated after each switching. S16. To maximize the number of available time slots, a time slot calculation model is constructed. The expression of the time slot calculation model is as follows: ; In the formula, Number of available time slots This represents the total number of time slots within a hopping beam period. For the number of switching times, For protection intervals; S17. Solve the time slot calculation model to select a time slot number from the minimum or maximum demand of the current wave positions to be allocated as a benchmark for allocation, calculate the utilization rate after allocation, select the time slot number that maximizes the utilization rate as the final time slot number for this allocation, and generate software-defined control instructions based on the final time slot number for this allocation.

[0028] Furthermore, the process of determining the number of consecutively allocated time slots after each handover using the uplink / downlink handover mechanism includes: generating the number of forward hop beam camping time slots using a convex optimization algorithm based on the downlink traffic volume of each wave position; generating the number of reverse hop beam camping time slots using the maximum remaining time slot priority algorithm based on the uplink traffic volume of each wave position; calculating the maximum transmission delay of each wave position at the current time based on the satellite ephemeris and dynamically updating the duration of the guard interval; setting the co-frequency reuse distance between beam clusters and planning the beam lighting sequence; arranging the downlink or uplink time slot requirements of all currently illuminated wave positions in descending order and dynamically allocating a segment of downlink or uplink time slots; after the allocation of this segment of time slots is completed, inserting the guard interval, performing uplink / downlink handover, and allocating reverse time slots; repeating the descending order arrangement of the downlink or uplink time slot requirements of all currently illuminated wave positions until the traffic requirements of all wave positions are met or the time slots within the hop beam cycle are exhausted.

[0029] In a preferred embodiment, in step S11, the network control center obtains the number of time slot requests required for each user's reverse transmission, including: S11.1. The network control center obtains the transmission rate requirements of each user uploaded by the user terminal; S11.2. Calculate the number of time slots required for the user's reverse transmission based on the user's transmission rate requirements, the preset frame length, and the effective data volume carried per time slot. The expression for the number of time slots required for the user's reverse transmission is as follows: ; In the formula, The number of time slot requests required for the reverse transmission of the i-th user. For the ceiling function, For the transmission rate requirement of the i-th user, For the preset frame length, The effective amount of data carried per time slot.

[0030] S2. The gateway station acquires forward data and encapsulates the forward data according to control commands to obtain encapsulated data. Using time-division multiplexing technology, the encapsulated data is sent to the low-Earth orbit satellite. In practice, the gateway station encapsulates the acquired forward link data according to the received control commands to obtain encapsulated data, and uses Time Division Multiplexing (TDM) technology to send the encapsulated data to the low-Earth orbit satellite through the feeder link. The principle of TDM technology is to divide the transmission time into periodically repeating time frames, each frame is further subdivided into several time slots, and each signal occupies one or more time slots to send data within the specified time slice, avoiding mutual interference.

[0031] S3. The low-orbit satellite performs beam-level switching on the encapsulated data according to the beam hopping pattern, and then sends the switched data to the user terminal through the downlink beam. In practice, after receiving the encapsulated data, the onboard beam-hopping controller of the low-Earth orbit satellite performs beam-level switching on the encapsulated data according to the beam-hopping pattern in the control command. This switches the data streams to the corresponding downlink beam channels for different target addresses. Subsequently, the satellite transmits the switched data to the corresponding user terminal through the phased array antenna via the appropriate downlink beam.

[0032] S4. The user terminal allocates resources to the received exchanged data based on control commands, obtains multi-beam uplink signals, and transmits the multi-beam uplink signals to low-orbit satellites through multi-frequency time division multiple access technology; In practice, after receiving downlink data, the user terminal configures its own resources based on the resource allocation information in the control command, generates a multi-beam uplink signal, whereby the resource allocation information includes time slots, frequency and power, etc., and transmits the multi-beam uplink signal to the low-Earth orbit satellite through multi-frequency time division multiple access (MF-TDMA) technology. The multi-beam uplink signal includes frequency division multiple access (FDMA), time division multiple access (TDMA) and code division multiple access (CDMA) signals.

[0033] S5. The low-orbit satellite performs on-board regeneration processing on the multi-beam uplink signal and transmits it back to the gateway station via the satellite-to-ground link.

[0034] It should be noted that the multi-beam uplink signal includes frequency division multiple access (FDMA) signal, time division multiple access (TDMA) signal, and code division multiple access (CDMA) signal.

[0035] In step S5, the low-orbit satellite performs on-board regeneration processing on the multi-beam uplink signal and transmits it back to the gateway station via the satellite-to-ground link, including: S51. Use a low-pass filter to separate the multi-beam uplink signal into multiple frequency division multiple access signals; S52. For each frequency division multiple access signal, a matched filter is used to extract the time slot synchronization of the time division multiple access signal to obtain a burst pulse signal. Based on the burst pulse signal, a despreader and a delay-locked loop are used to track the code phase of the code division multiple access signal to separate the burst signals of each user. S53. Perform maximum likelihood estimation of the initial carrier phase for the preamble sequence in the burst signal of each user to complete carrier synchronization and obtain the estimated carrier phase; S54. Based on the estimated carrier phase, the burst signals of each user are quadrature demodulated to obtain the baseband symbol sequence. The differential phase of adjacent symbols in the baseband symbol sequence is estimated and corrected for frequency offset to obtain a symbol sequence without frequency offset. S55. Demodulate and decode the symbol sequence without frequency offset to obtain user data packets, reconstruct the user data packets based on control commands to obtain downlink data streams, and send the downlink data streams to the gateway station.

[0036] In practice, after receiving the multi-beam uplink signal, the low-Earth orbit satellite first separates the mixed signal into multiple frequency division multiple access (FDMA) signals using a low-pass filter, and then uses maximum likelihood estimation to synchronize the initial carrier phase. Subsequently, a matched filter is used to extract the time slot synchronization of the time division multiple access (TDMA) signal, while a despreader and delay-locked loop (LLL) are used to track the code phase of the code division multiple access (CDMA) signal to separate the burst signals of each user one by one. Orthogonal demodulation is performed on the burst signals of each user to obtain a baseband symbol sequence. Frequency offset estimation is performed based on the differential phase of adjacent symbols, and the baseband symbols are corrected according to the estimated frequency offset value to obtain a signal without interference. The frequency offset symbol sequence is then processed; finally, the corrected symbol sequence is demodulated and decoded to obtain user data packets. The low-Earth orbit satellite aggregates data packets belonging to the same downlink beam according to a preset switching table, re-codes and modulates the channel, completes the reconstruction of the downlink data stream, and transmits it back to the gateway station via the satellite-to-ground link. This significantly suppresses mutual interference between signals. After demodulation and decoding are completed on the satellite, data packets are aggregated and reconstructed according to the switching table, enabling the low-Earth orbit satellite to have regenerative switching capabilities. It eliminates the need to transmit all the original data back to the gateway station, reducing the transmission pressure on the feeder link and enabling refined and dynamic management of network resources.

[0037] Furthermore, in step S54, after demodulating and decoding the frequency-offset-free symbol sequence, the following steps are also included: S54.1. Obtain data packets and target address information for each user; S54.2. According to the preset exchange table, the low-orbit satellite aggregates user data packets belonging to the same downlink beam, re-codes and modulates the channel, and obtains the reconstructed downlink data stream.

[0038] It should be noted that through the above steps S54.1 and S54.2, on-demand reconstruction and flexible routing of on-board data can be achieved, solving the problem that traditional transparent relay satellites can only perform signal frequency conversion amplification. By acquiring the data packets and target address information of each user, and according to the exchange table pre-configured by the network control center, data packets from different users destined for the same downlink beam are aggregated and re-channel coded and modulated to generate a downlink data stream adapted to the target beam. This endows the satellite with on-board regenerative switching capabilities, enabling it to flexibly schedule and reassemble data among multiple beams according to real-time service requirements. This avoids sending all the original data back to the gateway station for processing, which would result in additional transmission delays and feeder link bandwidth pressure, significantly improving the fine-grained management capability of beam resources and the overall transmission efficiency of the system.

[0039] In a preferred embodiment, the control commands are sent to the dedicated management channel of the low-Earth orbit satellite via a gateway station, and the network control center updates the control commands in real time according to changes in services.

[0040] like Figure 2 As shown, the second aspect of this embodiment provides a software-defined MF-TDMA multi-beam access device, including: The network control center is used to acquire users' resource requests and generate software-defined control commands based on the users' resource requests and the overall network service load. The control commands include beam switching patterns. The control commands are sent to low-Earth orbit satellites through gateway stations and simultaneously to user terminals. The gateway station is used to acquire forward data and encapsulate the forward data according to control commands to obtain encapsulated data. Using time division multiplexing technology, the encapsulated data is sent to the low-Earth orbit satellite. Low-Earth orbit satellites are used to perform beam-level switching on encapsulated data according to beam hopping patterns and then transmit the switched data to user terminals via the corresponding downlink beams. The user terminal is used to allocate resources to the received exchanged data based on control commands, obtain multi-beam uplink signals, and transmit the multi-beam uplink signals to low-orbit satellites through multi-frequency time division multiple access technology. Low-orbit satellites are also used for on-board regeneration of multi-beam uplink signals and back to the gateway station via a satellite-to-ground link.

[0041] The working process, working details and technical effects of the software-defined MF-TDMA multi-beam access device provided in the second aspect of this embodiment can be found in the software-defined MF-TDMA multi-beam access method described in the first aspect, and will not be repeated here.

[0042] like Figure 3 As shown, the third aspect of this embodiment provides another software-defined MF-TDMA multi-beam access device, including a memory, a processor, and a transceiver connected in sequence. The memory stores a computer program, the transceiver sends and receives messages, and the processor reads the computer program and executes the software-defined MF-TDMA multi-beam access method as described in the first aspect. Specifically, the memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out (FIFO) memory, and / or first-in-last-out (FILO) memory, etc.; the processor may include, but is not limited to, a microprocessor of the STM32F105 series. Furthermore, the computer device may also include, but is not limited to, a power module, a display screen, and other necessary components.

[0043] The working process, working details and technical effects of the aforementioned software-defined MF-TDMA multi-beam access device provided in the third aspect of this embodiment can be found in the software-defined MF-TDMA multi-beam access method described in the first aspect, and will not be repeated here.

[0044] The fourth aspect of this embodiment provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions that, when executed on a computer, perform the software-defined MF-TDMA multi-beam access method as described in the first aspect. The computer-readable storage medium refers to a data storage medium, which may include, but is not limited to, floppy disks, optical disks, hard disks, flash memory, USB flash drives, and / or Memory Sticks. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0045] The working process, working details and technical effects of the aforementioned computer-readable storage medium provided in the fourth aspect of this embodiment can be found in the software-defined MF-TDMA multi-beam access method described in the first aspect, and will not be repeated here.

[0046] The fifth aspect of this embodiment provides a computer program product, including a computer program or instructions, which, when executed by a computer, are used to implement the software-defined MF-TDMA multi-beam access method as described in the first aspect.

[0047] The working process, working details and technical effects of the aforementioned computer program product provided in this embodiment can be found in the software-defined MF-TDMA multi-beam access method described in the first aspect, and will not be repeated here.

[0048] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A software-defined MF-TDMA multi-beam access method, applied to a communication system including a network control center, gateway station, low-Earth orbit satellite, and user terminals, characterized in that, include: The network control center obtains the user's resource request and generates software-defined control commands based on the user's resource request and the overall network service load. The control commands include beam switching patterns. The control commands are sent to the low-Earth orbit satellite through the gateway station and simultaneously to the user terminal. The gateway station acquires forward data and encapsulates the forward data according to control commands to obtain encapsulated data. Using time-division multiplexing technology, the encapsulated data is sent to the low-Earth orbit satellite. Low-Earth orbit satellites perform beam-level switching on the encapsulated data according to the beam hopping pattern, and then transmit the switched data to the user terminal via the downlink beam. The user terminal allocates resources to the received exchanged data based on control commands, obtains multi-beam uplink signals, and transmits the multi-beam uplink signals to low-Earth orbit satellites through multi-frequency time division multiple access technology; The low-orbit satellite performs on-board regeneration processing on the multi-beam uplink signal and transmits it back to the gateway station via the satellite-to-ground link.

2. The software-defined MF-TDMA multi-beam access method according to claim 1, characterized in that, The multi-beam uplink signal includes frequency division multiple access (FDMA) signal, time division multiple access (TDMA) signal, and code division multiple access (CDMA) signal; the low-Earth orbit satellite performs on-board regeneration processing on the multi-beam uplink signal and transmits it back to the gateway station via a satellite-to-ground link, including: A low-pass filter is used to separate the multi-beam uplink signal into multiple frequency division multiple access signals; For each frequency division multiple access signal, a matched filter is used to extract the time slot synchronization of the time division multiple access signal to obtain a burst pulse signal. Based on the burst pulse signal, a despreader and a delay-locked loop are used to track the code phase of the code division multiple access signal to separate the burst signals of each user. For each user's burst signal, the initial carrier phase is estimated by maximum likelihood estimation to complete carrier synchronization and obtain the estimated carrier phase. Based on the estimated carrier phase, the burst signals of each user are quadrature demodulated to obtain the baseband symbol sequence. The differential phase of adjacent symbols in the baseband symbol sequence is estimated and corrected for frequency offset to obtain a frequency offset-free symbol sequence. The symbol sequence without frequency offset is demodulated and decoded to obtain user data packets. The user data packets are reconstructed based on control commands to obtain downlink data streams, which are then sent to the gateway station.

3. The software-defined MF-TDMA multi-beam access method according to claim 2, characterized in that, After demodulating and decoding the frequency-offset-free symbol sequence, the process also includes: Obtain data packets and target address information for each user; Low-Earth orbit satellites aggregate user data packets belonging to the same downlink beam according to a pre-set exchange table, and then re-encode and modulate the channel to obtain a reconstructed downlink data stream.

4. The software-defined MF-TDMA multi-beam access method according to claim 1, characterized in that, The network control center obtains user resource requests, including: The network control center obtains the number of time slot requests required for each user's reverse transmission, divides each user's time slot requests into multiple time slot blocks according to consecutive time slots, and sorts the multiple time slot blocks in descending order according to the size of the time slot blocks to obtain a set of time slot blocks to be allocated. Initialize all available carriers in the communication system in numerical order and record the remaining time slots for each carrier; According to the preset allocation rules, the largest time slot block in the set of time slot blocks to be allocated is allocated to the carrier with the most remaining time slots. If multiple carriers have the same number of remaining time slots, the time slot block to be allocated is allocated to the carrier with the smallest number. After one round of allocation is completed, if there are still unallocated time slot blocks, the carriers are selected in descending order of the remaining time slots of each carrier for the next round of allocation, until all time slot blocks are allocated or the remaining time slots of all carriers are zero, at which point the user's resource request is obtained.

5. The software-defined MF-TDMA multi-beam access method according to claim 4, characterized in that, The network control center obtains the number of time slot requests required for each user's reverse transmission, including: The network control center obtains the transmission rate requirements of each user uploaded by the user terminal. The number of time slots required for the user's reverse transmission is calculated based on the user's transmission rate requirements, the preset frame length, and the effective data volume carried per time slot. The expression for the number of time slots required for the user's reverse transmission is as follows: ; In the formula, The number of time slot requests required for the reverse transmission of the i-th user. For the ceiling function, For the transmission rate requirement of the i-th user, For the preset frame length, The effective amount of data carried per time slot.

6. The software-defined MF-TDMA multi-beam access method according to claim 1, characterized in that, The beam hopping pattern is a time slot block of each wave position within a beam hopping cycle, wherein each wave position's time slot block consists of an uplink time slot, a downlink time slot, and a guard interval. The duration of the protection interval is the difference between the maximum and minimum satellite-to-ground transmission delay within the corresponding wavelength.

7. The software-defined MF-TDMA multi-beam access method according to claim 1, characterized in that, Based on user resource requests and overall network service load, software-defined control commands are generated, including: Within a hopping beam cycle, the uplink / downlink switching mechanism is used to determine the number of consecutive time slots allocated after each switching. With the goal of maximizing the number of available time slots, a time slot calculation model is constructed, and the expression of the time slot calculation model is as follows: ; In the formula, Number of available time slots This represents the total number of time slots within a hopping beam period. For the number of switching times, For protection intervals; The time slot calculation model is solved to select a time slot number from the minimum or maximum demand of the current wave positions to be allocated as a benchmark for allocation, and the utilization rate after allocation is calculated. The time slot number that maximizes the utilization rate is selected as the final time slot number for this allocation, and software-defined control instructions are generated based on the final time slot number for this allocation.

8. The software-defined MF-TDMA multi-beam access method according to claim 1, characterized in that, The control commands are sent to the dedicated management channel of the low-Earth orbit satellite through the gateway station, and the network control center updates the control commands in real time according to changes in services.

9. A software-defined MF-TDMA multi-beam access device for implementing the method according to any one of claims 1 to 8, characterized in that, include: The network control center is used to acquire users' resource requests and generate software-defined control commands based on the users' resource requests and the overall network service load. The control commands include beam switching patterns. The control commands are sent to low-Earth orbit satellites through gateway stations and simultaneously to user terminals. The gateway station is used to acquire forward data and encapsulate the forward data according to control commands to obtain encapsulated data. Using time division multiplexing technology, the encapsulated data is sent to the low-Earth orbit satellite. Low-Earth orbit satellites are used to perform beam-level switching on encapsulated data according to beam hopping patterns and then transmit the switched data to user terminals via the corresponding downlink beams. The user terminal is used to allocate resources to the received exchanged data based on control commands, obtain multi-beam uplink signals, and transmit the multi-beam uplink signals to low-orbit satellites through multi-frequency time division multiple access technology. Low-orbit satellites are also used for on-board regeneration of multi-beam uplink signals and back to the gateway station via a satellite-to-ground link.

10. A software-defined MF-TDMA multi-beam access device, characterized in that, The device includes a memory, a processor, and a transceiver that are sequentially and communicatively connected. The memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer programs and execute the software-defined MF-TDMA multi-beam access method as described in any one of claims 1 to 8.

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